The structural features of conventional eyewear are generally catalogued into two groups. The first group includes goggles, the frames of which usually include a portion contoured in accordance with and abutting the user's face around the eyes, and are retained on the user's head by an elastic strip. Therefore, semi-flexible plastic materials are conventionally used for the frames of goggles in order to provide proper flexibility and resiliency which are also advantageous for attachment of lenses to thee frames of the goggles. Goggles are used in special circumstances such as during swimming, skiing, or other sports rather than for everyday life.
The second group of eyewear includes a variety of eye glasses which are all characterized as having a substantially rigid frame with a pair of temples for retaining the eye glasses on the user's head. Metal or substantially rigid plastic materials are conventionally used for the frames of eye glasses, and the latter is more widely and typically used, for example, for sunglasses.
Nevertheless, there has been a problem of securely attaching lenses to eye glasses frames, and more particularly to the substantially rigid plastic frames of eye glasses. The plastic frames of eye glasses typically define a pair of apertures for receiving a pair of lenses therein, respectively. Such lenses are usually made of glass or rigid transparent plastics, which have limited resiliency properties. Conventionally, the lenses are attached to the respective apertures of the frame of a pair of eye glasses using a “click in” action which forces elastic deformation of either or both the lenses and a portion of the frame body defining the respective apertures when each lens is pressed into one of the apertures. However, neither the rigid lens nor the portion of the rigid frame body defining the aperture provides a significant elastic deformation during the “click in” action for a more secure attachment of the lens to the frame. Eye glasses users unfortunately sometimes suffer the loss of lenses from their eye glasses because the lenses have become less firmly retained within the apertures of the frame over a period of usage. It should be noted that the conventional “click in” type of attachment of lenses to the apertures of the eye glasses frames requires very accurate geometry of both the peripheries of lenses and the apertures of the frames, when the lenses and frames are fabricated in separate manufacturing processes.
Therefore, there is a need for a secure attachment of lenses to the apertures of frames of eye glasses, particularly to the apertures of substantially rigid plastic frames of eye glasses.